Coral calcification in massive Porites in the nearshore region of the northern Great Barrier Reef

Ten massive Porites colonies were collected from the fringing reefs of each of 4 inshore islands of the Great Barrier Reef in January 2004. Two reefs were located in the Far Northern Region (Hannah Island and Hay Islands) and two reefs were located approximately 450 km away in the Northern Region (High Islands and Kent Islands). All colonies were >=30 cm in diameter and were selected from the leeward side of each island at depths between 1 and 3 m below the lowest astronomical tide. Of the 40 colonies collected, 38 colonies were found to be suitable for the analysis of growth parameters.A slice, approximately 7mm thick, was cut from the centre of each colony, dried and X-rayed. The positive X-ray prints were used to identify two tracks on each slice with clear annual density bands and also to date these bands. Skeletal density was measured at 0.25 mm intervals along each track using a gamma densitometer. From these measurements, spatial and temporal variations in three annual coral growth parameters; annual extension (linear distance between adjacent density minima (cm/y)), skeletal density (g/cm³) and calcification rate (the product of skeletal density and annual extension, g/cm²/y) were calculated. The three variables were then averaged across the two densitometer tracks for each corresponding growth year.While the age of annual growth bands ranged from 1971 to 2003, few bands were recorded before 1988 and analysis was focused on the period 1988-2003. Average monthly SST for each region were obtained from the HadISST 1.1 database, available from the British Atmospheric Data Centre. This study was carried out to examine temporal and spatial variation in growth parameters of massive Porites corals from two inshore regions of the Great Barrier Reef. The relationship between growth parameters and sea surface temperature (SST) was also investigated.

2004年1月，研究人员从大堡礁（Great Barrier Reef）4座近岸岛屿的岸礁中各采集10个滨珊瑚属（Porites）大型群落。其中2座礁体位于远北区（Far Northern Region）：汉娜岛（Hannah Island）与海伊岛（Hay Islands）；另外2座礁体则位于约450公里外的北区（Northern Region）：海群岛（High Islands）与肯特群岛（Kent Islands）。
所有采集的珊瑚群落直径均≥30厘米，均选取自各岛屿背风侧、最低天文潮位以下1至3米水深的区域。本次共采集40个珊瑚群落，其中38个可用于生长参数分析。
从每个群落的中心处切取厚度约7毫米的切片，经干燥后进行X射线成像。利用X射线正片识别每一切片上具有清晰年密度纹层的两条采样轨迹，并对这些纹层进行定年。使用伽马密度计（gamma densitometer）沿每条轨迹以0.25毫米的间隔测定骨骼密度。基于上述测量结果，计算得到三项年度珊瑚生长参数的时空变化特征：年度延伸率（相邻密度最小值间的线性距离，单位：厘米/年）、骨骼密度（单位：克/立方厘米）以及钙化率（骨骼密度与年度延伸率的乘积，单位：克/平方厘米/年）。随后针对每个生长年份，将两条密度计采样轨迹得到的三项变量取平均值。
尽管年度生长纹层的形成年代介于1971年至2003年之间，但1988年之前的纹层记录较少，因此本次分析聚焦于1988年至2003年的时段。各区域的月平均海表温度（sea surface temperature, SST）数据取自HadISST 1.1数据库，该数据库可从英国大气数据中心（British Atmospheric Data Centre）获取。
本研究旨在探究大堡礁两座近岸区域的大型滨珊瑚生长参数的时空变化特征，并分析生长参数与海表温度之间的关联。